Housings or chassis having removable covers are commonly used for storing eight or more printed circuit boards in a parallel, front-to-back arrangement. Computer systems and network servers often require substantial numbers of individual circuit boards. Each of the boards in a particular housing is typically tied to a housing mother board using appropriate strip connectors each having a plurality of contact pads. The mother board of each housing is tied to the system or network using serial or parallel communication lines. The circuit boards can also include various input/output (I/O) connectors along the rear edge. When the boards are mounted in respective strip connectors on the mother board, the I/O edge connectors are accessible through ports in the rear housing side wall.
When the number of circuit boards required exceeds the volume of a standard housing, additional chassis or housings must be employed. Multiple chassis are typically arranged in a vertical stack in a rack. The rack and each chassis include prealigned mounting holes that enable each chassis to be bolted to the rack at an appropriate elevation. To save space, each chassis is usually mounted as close to the others as possible.
FIG. 1 details an exemplary rack 20 holding three vertical circuit board chassis 22, 24 and 26 according to the prior art. The rack 20 includes two front posts 28 and two rear posts 30 in this example. The rack can include only a pair of front posts 28 in an alternate arrangement. The front posts 28 can include a series of evenly spaced holes 32 along their lengths. The holes, and corresponding mounting holes or slots in each chassis (not shown) receive threaded fasteners 34 that secure the respective chassis to the rack 20. The lower chassis 24 and 26 are separated from each other and from the upper chassis 22 by respective gaps g. The gaps g are minimized, generally, to maximize vertical storage capacity of the rack system. As an example, the interior construction of the top chassis 22 is exposed. The top cover 40 is shown removed. Screws 42 are used to secure the cover 40 to the underlying housing. A variety of cover shape and securing arrangements are used. In all conventional arrangements, the top is removed to access circuit boards 46 stored inside. The circuit boards 46 are arranged in parallel, from front to back of the chassis. Each of the circuit boards 46 is attached to a respective female multiple-contact strip connector (connector 48 for example) via a corresponding male strip connector 50. The connectors are interengaged by applying downward pressure (arrow 52) to the board 46, and disengaged by applying opposing upward tension to the board 46. This connector arrangement requires that the interior of the chassis be accessed through the top. That is, sufficient room to slide the connectors together and pull the connectors apart exists when the top is opened.
Each chassis front panel 56 includes evenly spaced ports 58 through which various I/O connectors, status lamps and ports 60 are exposed. Besides acting as a series of port holes, the front panel 56 usually provides part of the chassis' structural integrity.
The gap g is usually too small to remove the top cover of lower chassis 24 or 26. Likewise, the overlying chassis obstruct installation and/or removal of circuit boards. Hence, to service the underlying chassis, the overlying chassis must be disassemble from the rack 20. This increases service time and labor, and may increase the chance of handling damage to components not being serviced due to droppage, accidental disconnection of components and the like.
Accordingly, it is therefore an object of this invention to provide a chassis for storing a plurality of circuit boards in parallel that enables rapid installation and removal of circuit boards from the chassis without necessitating removal of the top cover of the chassis, and without requiring substantial disassembly of rack-mounted components. The boards should remain securely mounted in the chassis once installed.
This invention overcomes the disadvantages of the prior art by providing a rack mountable chassis for multiple circuit boards that enables side loading of individual circuit boards, thus eliminating the need to remove a chassis top cover, and, in turn, to remove the chassis from its rack. Rather, aligned with respective connectors in the chassis upon entry, and a lifter mechanism allows the boards to be raised and lowered within the chassis by an external handle to selectively place them respectively out of and into contact with the chassis connectors.
According to a preferred embodiment, the top of the chassis includes a plurality of parallel tracks each in alignment with respective strip connectors on the mother board located adjacent the opposing bottom of the chassis. Each track receives a top edge of a respective framework that encloses a circuit board. A strip connector is exposed along a bottom edge of the framework. The motherboard and circuit board strip connectors are arranged so that the downward pressure on the board away from the top, and toward the bottom of the chassis) causes a friction-fit connection between the boards. Likewise various I/O ports and/or connectors are exposed on a side edge of the framework. The chassis and the frameworks are each arranged so that the board can enter through an opening in the side of the chassis along a respective track. The board is located in the framework, upon entry in an retracted position, with the board's strip connector located above and out of interfering contact with the chassis' corresponding strip connector. Once the board has been fully inserted into the chassis, the framework can be operated to cause the board to move downwardly, placing the strip connectors into pressurable contact with each other.
According to the preferred embodiment, the framework includes a circuit board-carrying portion, and an interconnected track-engaging portion. The lifter mechanism is provided to interconnect the track-engaging and board-carrying portions. The track-engaging portion includes pins, that ride within sloped slots in the board-carrying portion. Upon installation of a board into the chassis, the track engaging portion is in an extended position, having an operative end positioned remote from the board-carrying portion. The track-engaging portion is moved pressurably into the chassis along the track to place the operative end adjacent the board-carrying portion. This movement, in turn, causes the pins to pass along the sloped slots, urging the board-carrying portion downwardly.
In the preferred embodiment, the rear edge of the board-carrying portion of the framework includes an alignment member, such as a channel piece with parallel, rearwardly extending interior walls that engage a corresponding alignment structure mounted at the rear of the chassis. The alignment structure can comprise one or more hooks that selectively capture corresponding posts or rollers disposed between the interior walls of the channel piece when the board-carrying section is lowered to place the board connector into engagement with the motherboard connector.
In the preferred embodiment, the edge of the board-carrying portion having the I/O includes a removable edge piece with an I/O slot that exposes the I/O connectors. In combination, the edge pieces define the side wall of the chassis and provide further support to the chassis.